Architecture
LatticeECP2/M Family Data Sheet
Lattice Semiconductor
If an EBR is pre-loaded during configuration, the GSR input must be disabled or the release of the GSR during
device Wake Up must occur before the release of the device I/Os becomes active.
These instructions apply to all EBR RAM and ROM implementations.
Note that there are no reset restrictions if the EBR synchronous reset is used and the EBR GSR input is disabled.
sysDSP™ Block
The LatticeECP2/M family provides a sysDSP block, making it ideally suited for low cost, high performance Digital
Signal Processing (DSP) applications. Typical functions used in these applications are Finite Impulse Response
(FIR) filters, Fast Fourier Transforms (FFT) functions, Correlators, Reed-Solomon/Turbo/Convolution encoders and
decoders. These complex signal processing functions use similar building blocks such as multiply-adders and mul-
tiply-accumulators.
sysDSP Block Approach Compared to General DSP
Conventional general-purpose DSP chips typically contain one to four (Multiply and Accumulate) MAC units with
fixed data-width multipliers; this leads to limited parallelism and limited throughput.Their throughput is increased by
higher clock speeds. The LatticeECP2/M, on the other hand, has many DSP blocks that support different data-
widths. This allows the designer to use highly parallel implementations of DSP functions. The designer can opti-
mize the DSP performance vs. area by choosing an appropriate level of parallelism. Figure 2-22 compares the fully
serial and the mixed parallel and serial implementations.
Figure 2-22. Comparison of General DSP and LatticeECP2/M Approaches
Operand
A
Operand
A
Operand
A
Operand
B
Operand
B
Operand
B
Operand
A
Operand
B
m/k
loops
Multiplier 0
x
x
x
Multiplier 1
M loops
Single
Multiplier
Multiplier k
x
Accumulator
(k adds)
+
Function implemented in
General purpose DSP
m/k
accumulate
Output
Function implemented
in LatticeECP2/M
sysDSP Block Capabilities
The sysDSP block in the LatticeECP2/M family supports four functional elements in three 9, 18 and 36 data path
widths. The user selects a function element for a DSP block and then selects the width and type (signed/unsigned)
of its operands.The operands in the LatticeECP2/M family sysDSP Blocks can be either signed or unsigned but not
mixed within a function element. Similarly, the operand widths cannot be mixed within a block. In the LatticeECP2/
M family the DSP elements can be concatenated.
The resources in each sysDSP block can be configured to support the following four elements:
2-21
LATTICE [ LATTICE SEMICONDUCTOR ]
